The present invention relates to a covering device for a nut and a covering device for a bolt head for the purpose of preventing others from unfastening the nut or bolt. More specifically, the present invention relates to technology useful in preventing theft of wheels from cars.
In general, 4-6 bolts are provided on a wheel support member to which a vehicle wheel is attached. The wheel is affixed to the wheel support member via this plurality of bolts. There are constructions where these bolts and nuts project out from the wall surface of the wheel hub. There are also constructions where these bolts and nuts are positioned in the interior of a bolt nut storage cavity on the wheel hub.
In the prior art, hexagon box nuts with tapped holes formed in them and normal hexagon nuts with through tapped holes are used as nuts for axing wheels. Because these nuts can be fastened and loosened using a normal wrench, they are ineffective in preventing the theft of wheels.
Referring to FIGS. 38-40, in the prior art, a nut device for affixing wheels, comprising a special nut 210 with an approximately cylindrical outer perimeter surface and a special wrench tool 215 that can rotate special nut 210, has been put into practical use. On the outer perimeter portion of nut 210, a plurality of vertical grooves 211 is formed irregularly in the circumferential direction. A tube part 216, which can receive nut 210, and a hexagonal part 217, which is for rotating with a normal wrench, are formed on wrench tool 215. A plurality of projection parts 218, which correspond to the plurality of vertical grooves 211, is formed on the inner surface of tube part 216.
With this nut device, special nut 210 can be fastened or loosened with a standard wrench via special wrench tool 215. The circumferential arrangement pattern of the plurality of vertical grooves 211 is not constant. By having a different pattern for each nut device, there can be a plurality of combinations, and a plurality of types of special nut 210 can be used Naturally, for each special nut 210, a special tool 215 is used Four of one type of special nut 210 and one wrench tool 215 that fits these are sold as a set.
However, if the number of types of special nuts 210 and wrench tools 215 is increased, the manufacturing costs become high. As a result, there can not be too many types. In this situation, those who have acquired all the types of wrench tools 215 can unfasten all types of special nut 210 relatively easily, and, as a result, they can steal the wheels.
In Japanese Utility Model Registration Number 2573547, Japanese Examined Utility Model Publication Number 8-30481, Japanese Examined Utility Model Publication Number 7-16095, Japanese Utility Model Registration Number 2559099, and the like, various locking devices for preventing wheel theft have been proposed. However, all of these locking devices have problems of having too many pieces, having complex constructions and high manufacturing costs, and the like.